Deduplication of data stored in a data repository may be useful in multiple contexts. In one example, a person may combine multiple contact lists (e.g., an email contact list, a social network contact list, and a mobile phone contact list) and wish to remove duplicate entries. In another example, a team of recruiters may be prohibited (e.g., for legal, company policy or best practice reasons) from contacting candidates that the team has previously contacted during a time period (e.g., in the last six months). Thus, when composing a message to a potential candidate, the recruiter may wish to compare the candidate with previously contacted candidates to determine if the potential candidate has previously been contacted. As the foregoing illustrates, techniques for deduplication of data stored in a data repository and techniques for integrating a messaging service with a deduplicator may be desirable.